German Patent No. DE 40 03 228 A1 describes a fuel injector in which a fuel filter on the inlet end of the fuel injector is pressed into the fuel inlet port. On the circumference, this fuel filter is provided with a brass ring, for example, which forms the pairing together with the wall of the fuel inlet port when the fuel filter is pressed into place. The brass ring surrounds a ring-shaped solid plastic section of the base body of the fuel filter, from which three webs, for example, extend in the longitudinal direction up to a common bottom section, the actual filter screen being extrusion coated in these subareas. An adjusting sleeve downstream from the fuel filter acts to adjust the spring pre-load of a return spring in contact with the adjusting sleeve.
In addition, some conventional fuel injectors include the adjusting sleeve and the fuel filter as a so-called combination part, i.e., the two functions of adjustment of the spring pre-load of a return spring in contact with the adjusting sleeve and filtering of the inflowing fuel are integrated into one part (as described in U.S. Pat. Nos. 5,335,863 A, and 6,434,822 B1, and European Patent Nos. EP 1 296 057 B1, EP 2 426 351 A1, EP 1 377 747 A1). All of the conventional approaches are characterized in that a press area is provided in the area of the adjusting sleeve and enters into a press fit with the wall of the connecting nozzle surrounding it, and this press fit is chosen to be so tight that the spring tension remains constant over the service life of the fuel injector, i.e., there is no slippage of the adjusting sleeve.